Method of preparing and using hectographic masters



United States Patent 16 Claims. E01. 96-30) The present invention relates to a hectographic method for forming hectographic copies of a hectographic master sheet. According to the present invention, a photographic reproduction is produced on a light sensitive material, such as a silver halide emulsion which contains a finely and evenly distributed water insoluble dye stuff component which is preferably colorless or only slightly colored. Of this material, a positive relief mirror image of the original is photographically produced under utilization of the Herschel effect.

The projection of the original image may be carried out by reflex with a conventional photocopy device through the light permeable foil. In the case of transparent originals, it is also possible to project the image onto the photo-sensitive layer by passing light through the transparent original onto the photo-sensitive layer. The photo-sensitive emulsion is to be previously exposed to ultraviolet light and this pre-exposure is neutralized by carrying out the image transferring exposure with relatively long wave yellow light, thus utilizing the Herschel effect.

It has been suggested previously to incorporate one component of the dye stuff in the printing form and the other one in the copying liquid. It has also been proposed to oxidize the printing form after development and to treat the printing form or master sheet in an acid bath prior to making copies thereof.

These prior methods are connected with certain disadvantages such as are for instance inherent in the use of an acid bath or in incorporating a dye stuff component in the copying liquid.

It is therefore an object of the present invention to provide a hectographic copying method which is not subject to such disadvantages.

It is a further object of the present invention to provide a method of producing a hectographic master sheet which may be copied in such a manner so as to avoid the disadvantages of prior art methods.

Other objects and advantages of the present invention will become apparent from a further reading of the description and of the appended claims.

With the above and other objects in view, the present invention contemplates in a method of forming a hectographic master sheet by photographic reproduction of an original image under utilization of the Herschel effect, the steps of forming a latent positive mirror image of said original image in a silver halide emulsion layer having distributed therethrough a substantially water insoluble and substantially non-coloring component of a chromogenic dye stuif adapted to react with a second component under formation of a printing ink, and developing said latent image with a hardening developer containing said second component and adapted to reduce silver halide so as to form a master sheet carrying a relief image including the thus formed printing ink so that when an imprint of said master sheet is made on a copy sheet, said image is transferred to said copy sheet.

Thus, according to the present invention, it is now possible to develop the master and to activate the dye stuff under formation of a printing ink, in a single treat- 3,241,965 Patented Mar. 22, 1966 ing bath, possibly passing the developed master thereafter through a cleaning bath.

According to the present invention, a component of a dye stuff which is formed by chromogenic development is incorporated in the gelatin layer of the master. Preferably, an indophenol is used as such dye stufi component. The developing liquid for the master will then contain the second component of such dye stuif which is formed by chromogenic development, preferably a derivative of p-phenylene diamine, such as N,N-dimethyl-p-phenylene diamine, which will reduce the silver halide to silver and simultaneously will form by oxidation the printing ink, preferably an indophenol dye stuff. It is preferred to use a developing liquid which also has tanning or hardening properties.

Copies of the thus formed master can be produced by imprinting the master sheet onto copy sheets in the presence of a copying liquid which preferably reacts neutral and also preferably contains alcohol. Preferably, the copying liquid is applied to the copy sheets so as to moisten the same prior to contact with the master.

The hardening properties of the developing liquid can be achieved by incorporating in the same suitable hardening substances such as pyrocatechol, or by choosing a derivative of p-phenylene diamine which possesses chromogenic and hardening properties.

For instance, phenols or substituted phenols such as alpha-naphthol or alpha-oxynaphthoic acid anilide in finely subdivided form may be worked into the gelatin layer as the dye stuff component thereof.

It is also possible to incorporate in the gelatin layer of the master as dye stuff component compounds having an enolic hydroxyl group, for instance pyrazolones and substituted pyrazolones, for instance 1-phenol-3- methyl-S-pyrazolone or anilides such as aceto-acetic acid anilide.

According to a further embodiment of the present invention, several dye stuff components such as those described above are incorporated in a plurality of layers of the gelatin emulsion next to each other or above each other so that after chromogenic development a variety of differently colored printing inks are formed on the master.

It is a particular advantage of the present invention that it is now possible in a single bath to develop the master as well as to activate the dye stuff therein. Furthermore, copies can be made with a neutral copying liquid, particularly with an alcohol-containing copying liquid in the same manner in which such copies can be made from suitable prior art master sheets.

Cleaning of the master from the expanded gelatin of the image-free portions may be carried out for instance by pressing against and again removing a sheet of absorbent paper from the master, or, the gelatin may be removed from the image-free portions of the master in a special cleaning bath.

It is a particular advantage of the present invention that the printing ink will be formed only at the image forming portions of the master while the gelatin layer which corresponds to the image-free portions of the master will be incapable of developing the dye stuff or printing ink. Due to this fact it is even possible to use a developer, for instance a paraformaldehyde developer which causes hardening or hardening throughout of the entire gelatin layer, i.e. of the exposed as well as of the unexposed portions. In the latter case, the thus hardened gelatin of the image-free portions need not be removed by washing or cleaning. The same result, namely retention of the entire gelatin layer can also be accomplished by pre-hardening the gelatin layer on the master or forming the gelatin layer of a self-hardening gelatin. Thereby, a further simplification of the entire process is accomplished because the somewhat involved removal of the gelatin layer corresponding to the image-free portions of the master has not to be carried out, and consequently any cleaning bath will not be contaminated with such removed gelatin, and furthermore, according to the present invention, it will be prevented that undesirable coloring or toning occurs at the image-free portions of the master.

According to the method of the present invention, it is possible to carry out all chemical reactions which are required for developing of the master in a single bath, whereby even the subsequent cleaning bath may be eliminated.

According to the present invention, it is not necessary to carry out a special oxidizing or activating reaction and this again makes it possible to carry out the invention with relatively simple developing devices and, furthermore, will eliminate a cause of oxidation and corrosion of the apparatus since special oxidizing agents or acids are not employed. In addition, copies may be run off the master according to the present invention with the help of a neutral copying liquid. The absence of acidic copying liquid will again prevent damage to the copying apparatus.

The following examples are given as illustrative only of the present invention, the invention, however, not being limited to the specific details of the examples.

EXAMPLE I A photographic paper having a direct positive silver halide gelatin layer in which as dye stuff component alpha-naphthol (Formula I) has been incorporated, is exposed by reflex with light for relatively long wave lengths, for instance, with yellow light, while located underneath a positive image which is to be reproduced.

Formula I The thus exposed layer is then developed With a hardening developer which contains as the second dye stuff component N,N-dimethyl-p-phenylene diamine (Formula Formula II C Ha Upon development, a blue printing ink consisting of an indophenol (Formula III) is formed which in the hardened image portions is incorporated in the positive mirror image.

Formula III The exposed and swollen portions of the gelatin layer are removed by pressing against the gelatin layer a blotting paper or the like, or by washing with warm Water. Copies may be made of the thus completed master in a conventional hectographic duplicating device.

EXAMPLE II A photographic paper having a direct positive silver halide gelatin layer, is exposed and developed as described in Example I. However, the dye stuff component which is incorporated in the gelatin layer is alpha-oxynaphthoic acid anilide (Formula IV).

4 Formula IV After developing, a bluish-green dye stuff or printing ink consisting of the indophenol of Formula V is formed.

Formula V C ONIIC (1H5 0 H3 N N= =0 0 I13 Further processing and copying of the printing form or master is carried out as described in Example I.

EXAMPLE III A photographic paper having a direct positive silver halide gelatin layer is placed underneath a positive transparent original image and is exposed through the same with yellow light. The gelatin layer of the paper contains as dye stuff component finely and evenly distributed l-phenyl-3-methyl-5-pyrazolone (Formula VI).

Upon development, purple dye stuff or printing ink, namely an indophenol (Formula VIII) will be formed at the image forming portions of the emulsion layer of the master.

Formula VIII Further processing of the master is carried out as described in Example I.

Without further analysis, the foregoing will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a method of forming a hectographic master sheet by photographic reproduction of an orginal image under utilization of the Herschel eifect, the steps of forming by exposure to long wave yellow light a latent positive mirror image of said original image in a silver halide emulsion layer which has been pre-exposed to ultraviolet light and which has having distributed therethrough a substance selected from the group consisting of phenols, alpha-naphthol, alpha-oxynaphthoic acid anilide, pyrazolones, and anilides as a substantially water insoluble and substantially non-coloring component of a chromogenic dye stuff adapted to react with a second component so as to form by such reaction a hectographic ink which is soluble in a copying liquid; and developing said latent image with a hardening developer containing N,N-dimeth yl-p-phenylenediamine as said second component and adapted to reduce silver halide so as to form a master sheet carying a relief image including the thus formed printing ink so that when an imprint of said master sheet is made on a copy sheet, said image is transferred to said copy sheet.

2. In the preparation of a hectographic printing master sheet, wherein a mirror image of an original is formed by photographic exposure, and said master sheet has an emulsion layer which is pre-exposed to ultraviolet light, long wave yellow light is used to neutralize said exposure and a hectographic copy is made from said master sheet, the steps of photographically exposing to long wave length light, under a positive original, an emulsion layer which comprises gelatin, a silver halide and a waterinsoluble color-former capable of forming a hectographic dye upon chromogenous development, until an image is formed in said emulsion layer on said master sheet; treating said master sheet with a color-developer capable of reducing the exposed silver halide to silver, and capable of simultaneously forming said hectographic dye by reaction with said color-former, whereby said master sheet is developed and simultaneously said hectographic dye is formed on said master sheet; and removing said gelatin in the image-free portions.

3. In the preparation of a hectographic printing master sheet, wherein a mirror image of an original is formed by photographic exposure, and said master sheet has an emulsion layer which is pre-exposed to ultraviolet light, long wave yellow light is used to neutralize said exposure and a hectographic copy is made from said master sheet, the steps of photographically exposing to long wave length light, under a positive original, an emulsion layer which comprises gelatin, a silver halide and a water-insoluble color-former capable of forming a hectographic dye upon chromogenous development, until an image is formed in said emulsion layer on said master sheet; treating said master sheet with a color-developer capable of reducing the exposed silver halide to silver, and capable of simultaneously forming said hectographic dye by reaction with said color-former, whereby said master sheet is developed and simultaneously said hectographic dye is formed on said master sheet; removing said gelatin in the image-free portions; moistening a copy sheet with a liquid which is a solvent for said hectographic dye; and contacting said master sheet with said copy sheet.

4. The method according to claim 3 wherein said solvent is a neutral liquid.

5. The method according to claim 4 wherein said solvent is an alcoholic liquid.

6. The method according to claim 2 wherein said colorformer is an indophenol, said color-developer comprises a derivative of a p-phenylenediamine, and said hectographic dye is an indophenyl dye.

7. The method according to claim 6 wherein said colordeveloper is a developing liquid which comprises N,N- dimethyl-p-phenylenediamine.

8. The method according to claim 6 wherein said colorformer additionally comprises a substance selected from the group consisting of phenols, alphanapthol and alphahydroxynaphthoic acid anilide.

9. The method according to claim 2 wherein said developer comprises a hardening agent for said gelatin.

10. The method according to claim 2 wherein said developer is a liquid comprising a tanning substance whereby hardening occurs both at the non-exposed and at the exposed areas of said emulsion layer.

11. The method according to claim 2 wherein said color-former comprises an enolic-hydroxyl-containing component which is a substance selected from the group consisting of pyrazolones and acetoacetic acid anilide.

12. The method according to claim 10 wherein said tanning substance is paraformaldehyde.

13. The method according to claim 2 wherein said color-former comprises l-phenyl-3-methyl-5-pyrazolone.

14. The method according to claim 2 wherein said gelatin emulsion comprises a plurality of superposed layers and a plurality of diiferent color-formers are incorporated at least one in each of said layers, whereby a plurality of colors are formed in said image on said master sheet.

15. The method according to claim 2 wherein said gelatin emulsion is hardened prior to said photographic exposure of the master sheet.

16. The method according to claim 10 wherein said developing liquid comprises pyrocatechol.

References Cited by the Examiner UNITED STATES PATENTS 2,054,261 9/ 1936 Lierg 9635 2,124,371 7/1938 Gschopf et al. 101-149.1 2,397,452 3/1946 White 96--3 X 2,903,964 9/1959 Taylor 96-28 X 2,912,325 11/1959 Maurer 9645 2,940,849 6/ 1960 Whitmore 9655 2,992,105 7/1961 Corley et al. 9655 3,012,885 12/1961 Abbott et al. 9635 X 3,049,994 8/1962 Raczynski et al. 101--149.5 3,096,711 7/1963 Ritzerfeld et al. 101149.4 3,152,898 10/ 1964 Hepher et a1 --33 NORMAN G. TORCHIN, Primary Examiner.

HAROLD N. BURSTEIN, Examiner. 

2. IN THE PREPARATION OF A HECTOGRAPHIC PRINTING MASTER SHEET, WHEREIN A MIRROR IMAGE OF AN ORIGINAL IF FORMED BY PHOTOGRAPHIC EXPOSURE, AND SAID MASTER SHEET HAS AN EMULSION LAYER WHICH IS PRE-EXPOSED TO ULTRAVIOLET LIGHT, LONG WAVE YELLOW LIGHT IS USED TO NEUTRALIZE SAID EXPOSURE AND A HECTOGRAPHIC COPY IS MADE FROM SAID MASTER SHEET, THE STEPS OF PHOTOGRAPHICALLY EXPOSING TO LONG WAVE LENGTH LIGHT, UNDER A POSITIVE ORIGINAL, AN EMULSION LAYER WHICH COMPRISES GELATIN, A SILVER HALIDE AND A WATERINSOLUBLE COLOR-FORMER CAPABLE OF FORMING A HECTOGRAPHIC DYE UPON CHROMOGENOUS DEVELOPMENT, UNTIL AN IMAGE IS FORMED IN SAID EMULSION LAYER ON SAID MASTER SHEET; TREATING SAID MASTER SHEET WITH A COLOR-DEVELOPER CAPABLE OF REDUCING THE EXPOSED SILVER HALIDE TO SILVER, AND CAPABLE OF SIMULTANEOUSLY FORMING SAID HECTOGRAPHIC DYE BY REACTION WITH SAID COLOR-FORMER, WHEREBY SAID MASTER SHEET IS DEVELOPED AND SIMULTANEOUSLY SAID HECTOGRAPHIC DYE IS FORMED ON SAID MASTER SHEET; AND REMOVING SAID GELATIN IN THE IMAGE-FREE PORTIONS.
 14. THE METHOD ACCORDING TO CLAIM 2 WHEREIN SAID GELATIN EMULSION COMPRISES A PLURALITY OF SUPERPOSED LAYERS ND A PLURALITY OF DIFFERENT COLOR-FORMERS ARE INCORPORATED AT LEAST ONE IN EACH OF SAID LAYERS, WHEREBY A PLURALITY OF COLORS ARE FORMED IN SAID IMAGE ON SAID MASTER SHEET. 